Hello
I have one game object that is relatively large and until a few minutes ago I could see and modify the object and the sub-objects in the hierarchy. But now I cannot see that Object, nor it’s colliders, and even the original model cannot be seen in the Scene tab.
However, the funny thing is that on the Game tab I can see the meshes and it reacts just as the last time I saved the prefab.
I need to edit that prefab but I cannot right now. Can someone help me?
Thanks in advance
check that all the layers are selected in the upper right corner of the screen in the editor window 
that fixed it for me
Wow, it really worked!
but this is what bugs me. I don’t remember going to that dropdown menu to deactivate it. Is there a shortcut to do that?
It happened to me when i zoomed in the scene and at the same time i changed the settings in upper right corner. Please make sure your unity is configured as shown in this picture below and try to zoom out; it might be the case. 